Nearby Earth-sized planets could support life, new study shows

An international team of astronomers has detected four Earth-sized planets orbiting tau Ceti, the closest sun-like star — two of which are located in the habitable zone and could support liquid water.

An international team of astronomers has detected four Earth-sized planets orbiting tau Ceti, the closest sun-like star two of which are located in the habitable zone and could support liquid water.

The new findings have been accepted for publication by the Astrophysical Journal and are available online.

Tau Ceti is located about 12 light-years from Earth and is visible to the naked eye. The planets are 1.7 Earth's mass, marking them as among the smallest planets ever found in a star's habitable zone. The outer two planets are likely candidates for alien life.

Sensitive new techniques allowed researchers to detect the planets by observing variations, or wobbles, in the tau Ceti's movement as small as 30 centimeters per second.

"We are now finally crossing the threshold where, through very sophisticated modeling of large combined data sets from multiple independent observers, we can disentangle the noise due to stellar surface activity from the very tiny signals generated by the gravitational tugs from Earth-sized orbiting planets," said co-author Steven Vogt, professor of astronomy and astrophysics at the University of California, Santa Cruz, in a statement.

Lead author Fabo Feng at the University of Hertfordshire, UK, says scientists are now in a much better position to detect Earth-like planets.

"Our detection of such weak wobbles is a milestone in the search for Earth analogs and the understanding of the Earth's habitability through comparison with these analogs," said Feng. "We have introduced new methods to remove the noise in the data in order to reveal the weak planetary signals.